A typical subsea installation can use an Electric Submersible Pump (ESP) within an inverted shroud. An ESP unit consists of a motor section, a seal section, and a pump section having an inlet and a discharge connected to production tubing and is used to provide artificial lift to liquid from a formation.
An inverted shroud can be used in combination with an ESP for use in gassy wells to divert the gas past the entrance of the ESP to reduce the possibility of gas locking. The shroud is a cylindrical steel tube that encompasses the ESP and is sized to allow clearance for fluid to pass both inside past the ESP and outside between the well casing and the shroud.
In gassy oil wells, gas and liquid enter the casing from the formation then both travel up the casing past the ESP unit to the top of the shroud. Due to gravity, the liquid can fall back down inside the shroud, which has an open top, and into the entrance of the pump. Gas slugs, however, effectively continue moving past the ESP. This reduces the chances for the ESP to experience gas locking due to gas slugs.
The assembly and installation of an inverted shroud with an ESP is very time consuming and difficult because the shroud, the pump, and lengths of production tubing must be assembled in unison as it is lowered into the hole. Parts for the assembly must be manufactured to strict tolerances in order to allow for proper assembly. Further, the diameter of the shroud limits the size of the motor that can be used for the ESP, which in turn affects the capability of the ESP to produce artificial lift.
A need exists for a technique that addresses the limitations and shortcomings described above. In particular a need exists for a technique to allow for an inverted shroud to be installed with an ESP in a timely manner and in a manner that does not limit the size of the motor that can be used. The following technique may solve these problems.